In Anti-Oedipus, Deleuze and Guattari claim that a general theory of society must be a generalised theory of flows. This is hardly a straightforward claim, and this paper attempts to examine the grounds for it. Why should socio-political theory be based on a theory of flows rather than, say, a theory of the social contract, or a theory of the State, or the questions of legitimation or revolution, or numerous other possible candidates? The concept of flow (and the related notions of code and stock), I argue, is derived from contemporary economic theory, and most notably John Maynard Keynes. Deleuze and Guattari remained Marxists, not only because they held that contemporary political philosophy must inevitably be centred on the analysis of capitalism, but also because they held, following Marx himself, that the Marxist analysis of capital must constantly be transformed and adapted to new conditions. Thus, while certain aspects of Marx's analysis disappear from Capitalism and Schizophrenia, they are supplemented by the addition of new concepts adequate to the contemporary state of capitalism. The paper concludes, then, with an analysis of the role played by the concepts of flow, code and stock in Deleuze and Guattari's political philosophy.